Hydrogenation

ABSTRACT

1. A PROCESS FOR SELECTIVELY HYDROGENATING THE RING UNSATURATION OF HETEROCYCLIC SULFUR-CONTAINING COMPOUNDS CONTAINED IN A HYDROCARBON FEEDSTREAM WHICH COMPRISES CONTACTING SAID FEEDSTREAM WITH HYDROGEN AND A MOLYBDENUM-ARSENIC CATALYST CONSISTING ESSENTIALLY OF ABOUT 2 TO 20 WEIGHT PERCENT MOLYBDENUM AND A MOLYBDENUM TO ARESNIC WEIGHT RATIO OF ABOUT 1:1 TO ABOUT 5:1 AND AN INORGANIC OXIDE SUPPORT UNDER HYDROGENATION CONDITIONS, SAID CATALYST HAVING BEEN REDUCED WITH HYDROGEN PRIOR TO SAID CONTACTING.

United States Patent 3,847,946 HYDROGENATION Marvin M. Johnson andDonald C. Tablet, Bartlesville, Okla., assignors to Phillips PetroleumCompany No Drawing. Original application Apr. 2, 1970, Ser. No. 25,239,now Patent No. 3,676,332. Divided and this application Mar. 9, 1972,Ser. No. 233,294

Int. Cl. C07d 63/02 US. Cl. 260329.3 13 Claims ABSTRACT OF THEDISCLOSURE A method and catalyst for reacting hydrogen with aromatichydrocarbons, with sulfur-containing acyclic and heterocyclic compounds,and with nitrogen-containing acyclic and heterocyclic organic compounds,the catalyst being comprised essentially of supported molybdenum andarsenic in their reduced forms.

This application is a divisional application of copending Ser. No.25,239, filed Apr. 2, 1970, now US. Pat. 3,676,332.

This invention relates to reacting hydrogen with organic compounds.

In one of its more specific aspects, this invention relates to reactinghydrogen with certain materials frequently found in hydrocarbon orpetroleum fractions.

In petroleum processing, a wide variety of materials, differingappreciably as to origin, are found in a single petroleum stream. Forexample, as a result of various processing, certain petroleum streamshave been found to contain sulfur-containing organic materials such asthiophenes and benzothiophenes, nitrogen-containing organic materialssuch as quinolines, and aromatics such as benzene. The elimination ofsuch materials from such streams generally involves a plurality ofsteps, each affecting one or more of such materials in a mannersimplifying their subsequent removal from the stock.

There has now been discovered a catalyst and a method by use of whichthe foregoing materials can be catalytically reacted with hydrogen, orhydrogenated, to effect their removal from the parent stream. The methodand catalyst of the present invention provide for such hydrogenation.

According to the present invention, there is provided a method forhydrorefining petroleum streams which comprise contacting said streamwith hydrogen and a supported catalyst comprised essentially ofmolybdenum and arsenic, said molybdenum and arsenic being in theirreduced forms, to hydrogenate at least a portion of the hydrogenatablematerials contained in said stream.

In one embodiment of this invention, when the stream contains organicsulfur-containing and/or nitrogen-containing compounds, the sulfurand/or nitrogen are converted to hydrogenated forms.

The hydrorefining can involve hydrogenation, hydrosulfurization andhydronitrogenation.

When the streams contain compounds such as unsaturated hydrocarbons,including olefins and aromatics, or unsaturated sulfur-containing and/ornitrogen-containing compounds, these compounds can be hydrogenatedaccording to the process of this invention.

Examples of the unsaturated compounds which can be hydrogenated areheXene-l, octene-l, benzene, toluene, cyclohexene, diallyl sulfide,butenyl mercaptan, thiophene, dibenzothiophene, dihydrothiophene,dihexenyl amine, decenylamine, quinoline, pyridine,2,4-dimethylpyridine, etc.

The sulfur-containing and nitrogen-containing compounds named above canalso be reacted with hydrogen in the presence of the catalyst of thisinvention to con- 3,847,946 Patented Nov. 12, 1974 vert their sulfurand/or nitrogen to hydrogen sulfide and ammonia. In addition, diethylsulfide, dibutyl amine, tetrahydrothiophene, and pyridine and the likecan be reacted with hydrogen to produce the corresponding saturatedhydrocarbon residue after the removal of the sulfur and/or the nitrogen.

Accordingly, it is an object of this invention to provide a simplifiedprocess for hydrogenation.

It is another object of this invention to provide a simply preparedcatalyst suitable for hydrogenation.

Hydrogenation of aromatic hydrocarbons, sulfur-containing acyclic andheterocyclic, and nitrogen-containing acyclic and heterocyclic compoundsis a useful process as applied to various hydrocarbon streams containingthese impurities encountered in the petroleum refining or petrochemicalfields. This is particularly so when these materials are found in minoramounts in various feedstreams to processes in which their presence isdeleterious as, for example, in contaminating catalysts, reducingyields, and the like. Accordingly, the method and catalyst of this invention find wide use in feed purification processes.

In general, the hydrorefining conditions of this invention involve atemperature of from about 250 F. to about 1000 F., pressures of fromabout p.s.i.g. to about 3000 p.s.i.g., a feed rate of about 0.1 to about10 LHSV and at an amount of hydrogen in the range of about 1 to about 50moles per mole of compound to be reacted with the hydrogen.

The method of this invention employs a catalyst, comprised essentiallyof molybdenum and arsenic in their reduced forms. Preferably, thecatalyst is supported. Alumina and activated alumina are most active,although other supports such as calcium aluminate, silica, titania, andmagnesium oxide, can be used.

In general, the catalyst is prepared by impregnating the granularsupport with molybdenum and arsenic in the form of their water solublecompounds, the impregnation being done with each compound eitherseparately or simultaneously. Thereafter, the impregnated support isdried in air at a temperature of about 850 to about 900 F. and reducedin a stream of hydrogen at a temperature of from about 800 F. to about1000 F.

The amount of molybdenum and arsenic with which the support isimpregnated will vary, depending upon the specific hydrogenation forwhich the catalyst is intended.

The finished catalyst will contain from about 2 to about 20 Weightpercent molybdenum and will have a molybdenum to arsenic weight ratio ofabout 1:1 to about 5:1. In its preferred composition, the catalyst willcontain from about 5 to about 10 weight percent molybdenum and will havea molybdenum to arsenic weight ratio of from about 3:1 to about 4:1 forhydrogenation of aromatics and for hydrodesulfurization andhydrodenitrogenation. For hydrogenation of heterocyclicnitrogen-containing and/or heterocyclic sulfur-containing compounds, theWeight ratio of molybdenum to arsenic is from about 1.5:1 to about2.521.

The method and catalyst of this invention are particularly suitable forthe hydrogenation of benzene when present in cyclohexane in an amount offrom about 2 to about 50 weight percent. For such purposes, thehydrogenation is conducted at a temperature of from about 250 to about550 F., at a pressure of from about 200 to about 1500 p.s.i.g., at afeed rate of from about 0.1 to about 10 liquid volumes per hour offeedstream per volume of catalyst (LHSV). Hydrogen is introduced intothe reaction in an amount of from about 3 to about 15 moles per mole ofbenzene contained in the feedstream. Under such conditions, the benzeneis hydrogenated to cyclohexane.

When employed for the hydrogenation of heterocyclic nitrogenand/ orsulfur-containing compounds, the method and catalyst are particularlysuitable for the conversion of compounds such as thiophene todihydrophiophene and/ or tetrahydrothiophene, particularly when presentin a hydrocarbon stream in an amount from about 2 to about 50 weightpercent. For such purposes, the reaction is conducted at a temperatureof from about 300 to 650 F., at a pressure of from about 500 to about3000 p.s.i.g, at a feed rate of from about 0.1 to about 10 LHSV, withhydrogen being introduced into the reaction in an amount of about 1 moleper mole of thiophene when the conversion is to the dihydrothiophene andwith hydrogen being introduced into the reaction in an amount of about 2moles per mole of thiophene when the conversion is to thetetrahydrothiophene. The hydrogenated heterocyclic is generallyremovable from the feedstream by distillation.

When employed for hydrorefining of sulfur and/ or nitrogen organiccompounds, the method and catalyst of this invention generally producegaseous sulfur-containing and nitrogen-containing compounds, such ashydrogen sulfide and ammonia, which are easily separated from thefeedstream. In these hydrogenations, the reaction is generally conductedat temperature of from about 550 to about 1000 F., at a pressure of fromabout 100 to about 1500 p.s.i.g, at a feed rate of from about 0.1 toabout 10 LHSV, with hydrogen being introduced into the reaction in anamount from about 0.5 to about moles per mole of total feed.

In general, the aforementioned reactions can be conducted simultaneouslywhen more than one of the hydrogenatable materials occurs in the samefeedstream. However, the hydrogenation of aromatics is preferablyconducted in the absence of sulfur compounds.

The method of this invention and procedures for preparing the catalystsare illustrated in the following examples.

EXAMPLE I A catalyst comprised of weight percent molybdenum and a moleratio of molybdenum to arsenic of about 3 to 1 was prepared using 1040mesh particulate alumina as a support.

Five (5) grams of H AsO were dissolved in 50 ml. water. Eighteen andfive-tenths (18.5) grams of (NH4) 6M07O24 2 were added to the resultingsolution. The white precipitate which formed on mixing was dissolved byadding 10 ml. of 28 percent ammonium hydroxide solution to the resultingsolution to form a clear solution.

The total volume of the clear solution was slurried with 100 grams ofdried alumina, the total volume of the clear solution being absorbed bythe alumina. The alumina was then dried for 48 hours at room temperatureand finally at 100 C. The dried alumina was heated in air at 960 F forthree hours to remove ammonia, after which the dried material wasactivated by heating in hydrogen at 800 F. for three hours. The finishedcatalyst contained 6.9 weight percent molybdenum and 1.9 weight percentarsenic.

EXAMPLE II A second catalyst containing about 7.5 weight percentmolybdenum and about 3.3 weight percent arsenic was prepared in themanner described in Example I, employing 8.7 grams of H AsO in 30 ml. ofwater with 18.5 grams (NH4)6M070244H20' and 40 ml. of 28 percent NHsolution. Ninety-four (94) grams of 10-40 mesh alumina were used.

These examples indicate methods of preparing catalysts of thisinvention.

EXAMPLE III The catalyst of Example I was employed for the hydrogenationof benzene.

A feedstream comprised of n-pentane and weight percent benzene wascontacted with the catalyst and with hydrogen, the mole ratio ofhydrogen to benzene being 8 to 1. The catalyst was maintained at 530 F.to 550 F.

at a pressure of 800 p.s.i.g. The feedstream charge rate was 2 LHSV,being equivalent to a benzene LHSV of about 0.3. The run was conductedfor a duration of seven hours. Initial conversion of the benzene tocyclohexane was 99.9 percent. Near the end of the seven-hour period, thetemperature of the catalyst was increased to 620 F. with the result thatthe conversion of benzene to cyclohexane decreased to 76 percent.

The above example indicates the efl ectiveness of the Catalyst andmethod of this invention in hydrogenating aromatics.

EXAMPLE IV The above run was repeated with a catalyst prepared inExample II. Under the initial conditions of Example III, the initialconversion of benzene to cyclohexane was percent, with conversiondecreasing to 51 percent after six hours.

The above data serve to further illustrate the use of the method andcatalyst of this invention in the hydrogenation of aromatics.

EXAMPLE V A feedstream was prepared consisting of 2.92 weight percentthiophene in benzene. This stream was contacted with a catalyst preparedin Example II under the conditions indicated below with the resultsnoted.

Run N o 1 2 3 Temperature, F 557 609 589 560 Hydrogen rate, molesfrnolethiopheue.-- 30 30 30 30 Pressure, p.s.i.g ,000 1,000 1,300 1, 300 Feedrate, LHSV 2 2 2 2 Product analysis, wt. percent:

Thiophene 1. 55 0. 630 0. 939 1. 46

Tetrahydrothiophene 0. 70 0.70 1. 07 0. 845 Conversion of thiophene,percent 47. 0 78. 5 68.0 50. 0

To benzene was added 3.6 weight percent thiophene. This was theequivalent of a sulfur content of 1.37 weight percent. The resultingblend was then contacted with a catalyst containing 6.9 weight percentmolybdenum and 1.9 weight percent arsenic supported on activated aluminawhich catalyst had been activated in hydrogen at 1000 F. Operatingconditions and results were as follows:

Operating conditions:

Temperature, F. 670-675 Pressure, p.s.i.g 800 Hydrogen, moles/molethiophene 23 Feed rate, LHSV 2 Thiophene content of product, Wt.percent:

After 1 hour operation 0.082

After 18 hours operation 0.023

The effluent gas was passed through cadmium sulfate solution. Yellowcadmium sulfide formed showing that H S was present in the efiluent gas.

These data indicate the operation and continued efiectiveness of themethod and catalyst of this invention in hydrogenating sulfur compoundsfor the purpose of desulfurizing aromatic mixtures containing thiophene.

EXAMPLE VII To benzene was added 1.7 weight percent dibenzothiophene.This was the equivalent of a sulfur content of 0.30 weight percent. Theresulting blend was then contacted with a catalyst comprised essentiallyof 6.9 weight percent molybdenum and 1.9 weight percent arsenicsupported on activated alumina which had been activated in hydrogen at1000 F. Operating conditions and results were as follows:

Operating conditions:

Temperature, F. 657 Pressure, p.s.i.g 800 Hydrogen, moles/moledibenzothiophene 120 Feed rate, LHSV 2 Sulfur content of product, wt.percent: 0.03 (limit of detection).

The above data illustrate employment of the catalyst and method of thisinvention in sulfur removal from aromatics by hydrodesulfurization.

EXAMPLE VIII To benzene were added both sulfur-containing andnitrogen-containing compounds, sulfur being added in the form ofdibenzothiophene and nitrogen being added in the form of quinoline.Dibenzothiophene was added in an amount of 1.7 weight percent to providea mixture having 0.30 weight percent sulfur and quinoline was added inan amount of v1.7 weight percent to provide a nitrogen content of 0.18weight percent in the mixture. A portion of the resulting stream wascontacted with that catalyst (I) employed in Example VII and a portionWas contact with a catalyst (II) comprised essentially of about 7.5weight percent molybdenum and about 3.3 Weight percent arsenic onalumina, the catalyst having been activated with hydrogen at 800 F.Results were as follows:

Catalyst 1 The above data indicate the operability of the catalyst andmethod of this invention over a wide range of conditions. The ability ofthe method and catalyst of this invention to hydrogenate such compoundsas are con cerned in the above examples, and particularlydibenzothiophene and quinoline, is of significance in that thesematerials are sometimes present in petroleum fractions and are difficultto remove.

It will be seen from the above that various modifications can be made tothe method and catalyst of this invention. However, such are consideredas being Within the scope of the invention.

We claim:

1. A process for selectively hydrogenating the ring unsaturation ofheterocyclic sulfur-containing compounds contained in a hydrocarbonfeedstream which comprises contacting said feedstream with hydrogen anda molybdenum-arsenic catalyst consisting essentially of about 2 toWeight percent molybdenum and a molybdenum to arsenic weight ratio ofabout 1:1 to about 5:1 and an inorganic oxide support underhydrogenation conditions, said catalyst having been reduced withhydrogen prior to said contacting.

2. A process according to claim 1 wherein said support is selected fromthe group consisting of alumina, calcium aluminate, silica, titania, andmagnesium oxide.

3. A process according to claim 2 wherein said hydrocarbon feedstreamcontains from about 2 to about 50 Weight percent of said sulfur compoundand said catalyst contains from about 5 to about 10 Weight percentmolybdenum, said molybdenum and said arsenic being present in a Weightratio of about 1.5:1 to about 2.5: 1.

4. The method of claim 2 in Which said hydrogenation is carried out at atemperature of from about 250 F. to about 1000 F., a pressure of fromabout p.s.i.g. to about 3000 p.s.i.g, a feed rate of about 0.1 to about10 LHSV, and employing at least a stoichiometric quantity of hydrogen.

5. The method of claim 2 in which said heterocyclic sulfur compounds ina hydrocarbon feedstock are selectively hydrogenated by contacting saidfeedstock and added hydrogen with said catalyst and a stoichiometricexcess of hydrogen based upon heterocyclic compound in the feedstock atan elevated temperature of about 300 to about 650 F. suflicient tosubstantially hydrogenate said heterocyclic sulfur compounds, andseparating hydrogenated heterocyclic compounds from the hydrogenatedfeedstock.

6. A process according to claim 5 wherein said feedstream comprisesaromatic hydrocarbons containing thiophene or dibenzothiophene.

7. A process according to claim 5 wherein said feedstream comprisesbenzene containing thiophene or dibenzothiophene.

8. The method of calim 2 in which thiophene or dibenzothiophene in adiluent is contacted with a catalyst containing about 7.5 weight percentmolybdenum and about 3.3 Weight percent arsenic on alumina.

9. A process for hydrodesulfurizing heterocyclic sulfurcontainingcompounds contained in a hydrocarbon feedstream which comprisescontacting said feedstream with hydrogen and a molybdenum-arseniccatalyst consisting essentially of about 2 to 20 weight percentmolybdenum and a molybdenum to arsenic weight ratio of about 1:1 toabout 5:1 and an inorganic oxide support under hydrodesulfurizingconditions, said catalyst having been reduced with hydrogen prior tosaid contacting.

10. A process according to claim 9 in which said hydrodesulfurization iscarried out at a temperature from about 550 to about 1000 F., at apressure of from about 100 to about 1500 p.s.i.g, at a feed rate of fromabout 0.1 to about 10 LHSV, with hydrogen being introduced into thereaction in an amount from about 0.5 to about 5 moles per mole of totalfeed.

11. A process according to claim 9 wherein said feedstream comprisesaromatic hydrocarbons containing thiophene or dibenzothiophene.

12. A process according to claim 9 wherein said feedstream comprisesbenzene containing thiophene or dibenzothiophene.

13. A process according to claim 9 in which thiophene ordibenzothiophene in a diluent is contacted with a catalyst containingabout 7.5 weight percent molybdenum and about 3.3 weight percent arsenicon alumina.

References Cited UNITED STATES PATENTS 5/1948 Boyd 260-329 U.S. Cl. X.R.

260-283 SY, 293.52, 329 R, 332.8, 583 R, 609 R, 667, 676 R, 683.9, 690

1. A PROCESS FOR SELECTIVELY HYDROGENATING THE RING UNSATURATION OFHETEROCYCLIC SULFUR-CONTAINING COMPOUNDS CONTAINED IN A HYDROCARBONFEEDSTREAM WHICH COMPRISES CONTACTING SAID FEEDSTREAM WITH HYDROGEN ANDA MOLYBDENUM-ARSENIC CATALYST CONSISTING ESSENTIALLY OF ABOUT 2 TO 20WEIGHT PERCENT MOLYBDENUM AND A MOLYBDENUM TO ARESNIC WEIGHT RATIO OFABOUT 1:1 TO ABOUT 5:1 AND AN INORGANIC OXIDE SUPPORT UNDERHYDROGENATION CONDITIONS, SAID CATALYST HAVING BEEN REDUCED WITHHYDROGEN PRIOR TO SAID CONTACTING.